---
id: 655a56a6a1168a8f201ba666
title: Step 53
challengeType: 20
dashedName: step-53
---

# --description--

Below the `BinarySearchTree` instance, create a list named `nodes` with the following integer values: `50`, `30`, `20`, `40`, `70`, `60`, `80`.

# --hints--

You should have a list named `nodes`.

```js
assert.match(code, /nodes/);
```

Your `node` variable should have the value `[50, 30, 20, 40, 70, 60, 80]`.

```js
assert.match(code, /nodes\s*=\s*\[\s*50\s*,\s*30\s*,\s*20\s*,\s*40\s*\s*,\s*70\s*,\s*60\s*,\s*80\s*\]/);
```

# --seed--

## --seed-contents--

```py
class TreeNode:
    def __init__(self, key):
        self.key = key
        self.left = None
        self.right = None

class BinarySearchTree:
    def __init__(self):
        self.root = None

    def insert(self,key):
        self.root = self._insert(self.root, key)

    def _insert(self, node, key):
        if node is None:
            return TreeNode(key)
        if key < node.key:
            node.left = self._insert(node.left, key)
        elif key > node.key:
            node.right = self._insert(node.right, key)
        return node

    def search(self, key):
        return self._search(self.root, key)

    def _search(self, node, key):
        if node is None or node.key == key:
            return node
        if key < node.key:
            return self._search(node.left, key)
        return self._search(node.right, key)

    def delete(self, key):
        self.root = self._delete(self.root, key)

    def _delete(self, node, key):
        if node is None:
            return node
        if key < node.key:
            node.left = self._delete(node.left, key)
        elif key > node.key:
            node.right = self._delete(node.right, key)
        else:
            if node.left is None:
                return node.right
            elif node.right is None:
                return node.left

            node.key = self._min_value(node.right)
            node.right = self._delete(node.right, node.key)
        return node

    def _min_value(self, node):
        while node.left is not None:
            node = node.left
        return node.key

    def inorder_traversal(self):
        result = []
        self._inorder_traversal(self.root, result)
        return result

    def _inorder_traversal(self, node, result):
        if node:
            self._inorder_traversal(node.left, result)
            result.append(node.key)
            self._inorder_traversal(node.right, result)

--fcc-editable-region--
bst = BinarySearchTree()

--fcc-editable-region--
```
